Which transition in `Li^(2 +)` would have the same wavelength as the `2 rarr 4` transition in `He^(+)` ion ?

Options

A. `4 rarr 2`
B. `2 rarr 4`
C. `3 rarr 6`
D. `6 rarr 2`

Answer

C

Explanation

`v=RC Z^(2)(1/n_(1)^(2)-1/n_(2)^(2))`
`v_(1)=RC Z^(2)(1/1^(2)-1/oo^(2))=RC Z^(2), v_(2)=RC Z^(2) (1/1^(2)-1/2^(2))=3/4 RC Z^(2)`
`v_(3)=RC Z^(2)(1/2^(2)-1/oo^(2))=1/4 RC Z^(2) :. upsilon_(1)-upsilon_(2)=upsilon_(3)`